package leetcode;

import java.util.Scanner;

public class LeetCodeMain73 {
    public static void main(String[] args) {
        Scanner in=new Scanner(System.in);
        long[] dp=new long[81];
        dp[0]=0;
        dp[1]=1;
        dp[2]=1;
        for (int i = 3; i <= 80; i++) {
            dp[i]=dp[i-1]+dp[i-2];
        }
        while (in.hasNext()){
            int from=in.nextInt();
            int to=in.nextInt();
            long sum=0;
            for (int i = from; i <= to; i++) {
                sum+=dp[i];
            }
            System.out.println(sum);
        }
    }
    public static void main1(String[] args) {
        Scanner in=new Scanner(System.in);
        while (in.hasNext()){
            String str=in.nextLine();
            String[] strings=str.split(" ");
            int count=0;
            int length=strings[1].length();
            if (length>strings[0].length()){
                System.out.println(0);
                continue;
            }
            for (int i = 0; i < strings[0].length();) {
                 if (i+length<=strings[0].length()&&strings[0].substring(i,i+length).equals(strings[1])){
                     count++;
                     i=length+i;
                 }else {
                     i++;
                 }
            }
            System.out.println(count);
        }
    }
}